Tomic Sladjana, Johnson Arthur E, Hartl F Ulrich, Etchells Stephanie A
Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.
FEBS Lett. 2006 Jan 9;580(1):72-6. doi: 10.1016/j.febslet.2005.11.050. Epub 2005 Dec 6.
Ribosome-bound trigger factor (TF) is the first chaperone encountered by a nascent polypeptide chain in bacteria. TF has been proposed to form a cradle-shaped shield for nascent chains up to approximately 130 residues to fold in a protected environment upon exit from the ribosome. We report that nascent chains of luciferase up to 280 residues in length are relatively protected by TF against digestion by proteinase K. In contrast, nascent chains of the constitutively unstructured protein alpha-synuclein were not protected, although they were in close proximity to TF by crosslinking. Thus, TF is not a general shield for nascent chains. Protease protection appears to depend on a hydrophobic interaction of TF with nascent polypeptides.
核糖体结合触发因子（TF）是细菌中新生多肽链遇到的首个伴侣蛋白。有人提出，TF会为长度达约130个残基的新生链形成一个摇篮状的保护罩，使其在从核糖体出来后能在受保护的环境中折叠。我们报告称，长度达280个残基的荧光素酶新生链相对受到TF的保护，免受蛋白酶K的消化。相比之下，组成型无结构蛋白α-突触核蛋白的新生链虽然通过交联与TF紧密相邻，但并未受到保护。因此，TF并非新生链的通用保护罩。蛋白酶保护似乎取决于TF与新生多肽之间的疏水相互作用。
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